Todd Lyons wrote:
>> The list is updated every 5 minutes based on Spamassassin scores. Any
>> servers that score less then zero are added but removed if they send a
>> message that scores over 5. Entries are only kept if they have been active
>> in last 28 days.
>>
>> Cannot believe how effective greylisting has been in reducing volume of
>> email.
>
> I wish that we could enable it globally. Lots of our customers nearly
> revolted when we tried to turn it on a couple years ago.
>
> I am going to work on making it a per mailbox option or a per domain
> option. Additionally, I want to make it so that any sender who is in
> a user address book will automatically be excluded from greylisting.
> Any of these will allow those who don't mind the delay to reap the
> benefits, whiles those who can't stand the fact that "my grandmother
> sent me an email 30 seconds ago and I still don't see it" won't have
> to talk to us. The combination of these items will make the system
> very malleable to the users' wants. Caveat: time permitting....
I'm not doing greylisting at the moment, but when I did do it, I came up
with a few configuration options to minimise when it took place. I
didn't want the greylisting to happen if the connecting host wasn't a
zombie so I came up with logic to detect non-zombies.
Don't greylist if one of these occurs:
1.) Zombies don't use encryption.
2.) If P0F detects the connecting host to be non-Windows (Used P0F for this)
3.) Zombies don't use the "SIZE" extension of ESMTP. So you check the
value of $smtp_command in the mail acl, ie: ${if match{$smtp_command}{\N
(SIZE=\d+)$\N}
I'm sure there were another couple of cases, but I haven't got the
config to hand anymore.
I also maintained a small whitelist of $sender_host_name values so I
didn't end up greylisting stuff like hotmail and facebook. Eg, my file
would contain stuff like:
*.hotmail.com
*.tfbnw.net
And I'd search it using:
${lookup{$sender_host_name}partial-lsearch{/path/to/whitelist}{true}{false}}
--
Mike Cardwell
(
https://secure.grepular.com/) (
http://perlcv.com/)
